Using information from 10-K filings of publicly traded firms, we identify economic connections among U.S. states. At the firm level, we document excess comovement in the returns and liquidity of public firms headquartered in economically connected states. At the aggregate level, the economic connections create spillover effects whereby economic shocks in a state affect its connected states and the U.S. economy. For example, a one percent production shock in California (Texas) is related to a

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... is related to a 6.71 (5.62) percent change in annual U.S. GDP growth, relative to the average GDP growth. Collectively, the network of publicly traded firms generates a channel that facilitates the propagation of local shocks across the U.S. economy. JEL Classification: C23, E32, E37, G10.